文档介绍:Wireless Power Experiments
Along the lines of the season's traditional blinkenlight projects I had the desire to build minimising the air-gap in the magnetic circuit.
A much more easily hackable solution for my toy display is to use so-called "evanescent wave coupling" to send power between tuned resonators. This allows efficient operation at much weaker coupling (much larger air-gap and/or no magnetic core material at all), as long as the resonators are fairly high-Q (low loss). Essentially we allow the much larger leakage inductances associated with low inductor coupling coefficients of "air core" transformers and then tune them out with capacitance, utilising the remaining mutual inductance to transfer power between the resonant circuits. In effect we utilise the large "buffering" capacity of high-Q tuned circuits to render an impedance match from the TX power source into the RX load over a poorly coupled path. As long as the inductors are physically small with respect to the free-space wavelength of the frequency of operation very little radiation (leakage of energy into space as radio emissions) will occur.
Yes, Tesla had this idea working in 1893, but there are a number of practical issues that limit the technique to niche applications, such as toothbrush and cellular telephone chargers where the coupling coefficient can be kept high, placing less demands on the circu